The price of domestic kerosene has rocketed in recent months - from 42p to 60p since February - making a typical 1,000 litre tank now worth around £600.

At the same time thefts, that were previously virtually unheard of, have increased.

Numbers are still low but they are going up - there were 27 reported incidents in North Yorkshire in the first four months of this year compared with 15 for the whole of 2007.

It is thought criminals may be watching for tankers en route to homes to make deliveries before striking.

BiB Insurance Brokers, which has offices in Bedale and Darlington and many rural customers across the region, is warning people to check their insurance policies to ensure they are covered for theft.

Veronica Ryan, retail operations manager, said: “We have contacted all our major insurers and they all take the same stance on the issue, namely that heating oil is covered under a home contents policy in the same way that garden furniture is covered.

“However, where they differ is in the policy limit. While some will cover up to £1,000, others insure for up to £500. With the price of oil continuing to rise, householders may find they are not fully covered if a newly-filled tank were drained by thieves and they might want to consider increasing their level of cover.”

Veronica added that householders should also take crime prevention measures.

She added: “Nobody wants to be a victim of crime and insurers do prefer people, wherever possible, to deter or at least delay thieves striking.

“Tanks should be located at the back of a property, preferably hidden from sight, with locks fitted, but of course this has to be balanced with the tank being accessible to the delivery driver.”